Elevator

ABSTRACT

An elevator has a pair of vertical and parallel T-section rails having central legs directed toward each other, forming a vertical plane, and formed with straight-across teeth. A car vertically displaceable between the rails has respective pairs of guides flanking the rails and restricting movement of the car horizontally only perpendicular to the plane. Respective sprockets rotatable on the car about axes perpendicular to the plane also have straight-across teeth meshing with the rail teeth. These sprockets lie in the plane and constitute the only restriction of horizontal movement of the car relative to the rails in the plane A drive synchronously rotates the sprockets to vertically displace the car along the plane on the rails. A manual safety can vertically displace the car along the rails. The guides are disks fixed to and sandwiching the sprockets. A brake on the car operatively engageable with the sprockets can arrest the car if the power fails or the like. An idler wheel between the rails above the car carries a cable having two ends, one of which is attached to the car. A counterweight is attached to the other cable end, the manual safety being coupled to the idler wheel.

FIELD OF THE INVENTION

The present invention relates to an elevator. More particularly thisinvention concerns a so-called zero-headroom elevator suitable forinstallation in existing structures.

BACKGROUND OF THE INVENTION

A standard elevator has a shaft vertically traversing a plurality ofdifferent floors of a building and a cabin or car guided on verticalrails in the shaft. A cable has one end connected to the top of the carand another end connected to a counterweight, and is looped over apulley mounted at the top of the shaft. A motor typically mounted in aroom that is provided on the building roof is connected to this pulley,so it can rotate it in one direction to raise the elevator and sink thecounterweight, and in the opposite direction to lower the elevator andraise the counterweight. This counterweight weighs about as much as thecar plus its average load, although for various reasons it can weighmore or less.

Such a structure requires that a substantial room be devoted to thecumbersome drive. Since the motor must be able to move the entirehigh-inertia mass of the elevator, the counterweight, and any passengersor freight, it must be fairly powerful, so it is fairly large. Whenprovided on the building roof this motor room uses normally otherwiseunused space. However, in an existing structure it is frequently notpossible to mount it on the roof, as the building is not designed forsuch a load. Providing the drive at the base of the shaft can solve thisproblem, although developing such underground space is normally verydifficult and expensive.

Hence recourse has been had to zero-headroom elevators which carry theirown drives, so that the elevator shaft need not extend much above orbelow the floors being served. Such an elevator can be installed in anexisting structure fairly easily.

The typical such system guides the car on four rails formed withstraight-across teeth, that is teeth whose flanks are formed by familiesof lines that are all parallel and perpendicular to the longitudinaldirection of the rails. These rails are engaged by respectivecomplementarily toothed sprockets carried by respective drive motors.Even when assembled to high tolerances, such an arrangement wearsrapidly, as the four sprockets inherently work somewhat differentiallyon the rails. Simple thermal expansion of the system can cause it tobind and wear excessively, and other factors can desynchronize thesprockets just as easily. Once such an arrangement has worn a little,the rate of wear increases rapidly.

Another arrangement has only two toothed rails that are engaged byrespective sprockets driven by respective worms sitting on the oppositeends of a motor shaft. To facilitate meshing, the sprockets have teetheach of whose one flank is inclined corresponding to the pitch of theworm and whose other flank is straight, that is parallel to the radius.Such teeth are unfortunately weaker one one side of the sprocket than onthe other. The teeth of the rail are complementarily formed as a row ofrecesses, that is they are not laterally open, and the teeth of one faceof the rail are narrower than the other rail face. Such teeth cannot beproduced easily, and are very difficult to machine to close tolerances.Hence such a system also wears rapidly.

It is also known for the two rails to have confronting faces formed asracks with straight-across teeth engaged by respective complementarysprockets driven by the same motor. Each rail has a pair of oppositelydirected guide grooves lying in a vertical plane perpendicular to theplane of the rails. Four respective angle irons carried on the car haveflanges projecting vertically into these grooves, thereby accuratelyguiding the car on the rails. Such an arrangement can bind readily andwill wear rapidly when not in perfect alignment.

In fact such zero-clearance elevators have all proven so troublesomethat they are no longer made or used on any meaningful scale.

OBJECTS OF THE INVENTION

It is therefore an object of the present invention to provide animproved zero-clearance or self-driving elevator.

Another object is the provision of such a zero-clearance or self-drivingelevator which overcomes the above-given disadvantages, that is whichdoes not present the considerable alignment and wear problems of theprior-art arrangements.

SUMMARY OF THE INVENTION

An elevator according to this invention has a pair of vertical andparallel T-section rails having central legs directed toward each other,forming a vertical plane, and formed with straight-across teeth. A carvertically displaceable between the rails has respective pairs of guidesflanking the rails and restricting movement of the car horizontally onlyperpendicular to the plane. Respective sprockets rotatable on the carabout axes perpendicular to the plane also have straight-across teethmeshing with the rail teeth. These sprockets lie in the plane andconstitute the only restriction of horizontal movement of the carrelative to the rails in the plane, A drive synchronously rotates thesprockets to vertically displace the car along the plane on the rails. Amanual safety can vertically displace the car along the rails. Theguides of this invention are disks fixed to and sandwiching thesprockets, the disks of each pair symmetrically flanking the elevatorplane.

In addition according to this invention a brake on the car operativelyengageable with the sprockets can arrest the car if the power fails orthe like. An idler wheel between the rails above the car carries a cablehaving two ends, one of which is attached to the car. A counterweight isattached to the other cable end, the manual operator being coupled tothe idler wheel.

With this arrangement the engagement of the teeth is all that limitsmovement of the car parallel to the plane. Thus any wear on one sidewill simply result in a slight lateral shifting of the car, withoutbinding or stressing the other side. The car will be self-centering, andeven if the gear teeth wear somewhat, the overall rate of wear will notincrease. In fact if the sprockets wear considerably all that willhappen is that the car will sit somewhat lower between the rails.Another advantage of this arrangement is that forces are automaticallydistributed evenly between the two sides of the car, so that wear willbe even.

According to this invention the manual operating means includes ahand-operable actuating element such as a crank or handwheel, atransmission connectable between the element and the idler wheel, andcontrol means connected between the element and the brake for releasingsame when the element is connected via the transmission to the wheel.The transmission can include a pair of bevel gears engageable like ajaw-type clutch with each other to couple the element to the wheel and acoupling chain. Thus this drive can be provided in the side of theshaft, normally at the uppermost story of the building incorporating theelevator.

DESCRIPTION OF THE DRAWING

The above and other features and advantages will become more readilyapparent from the following, reference being made to the accompanyingdrawing in which:

FIG. 1 is a small-scale vertical section through an elevator accordingto this invention with the car all the way to the top;

FIG. 2 is a large-scale horizontal section taken along line II--II inFIG. 1;

FIG. 3 is a view corresponding to a detail of FIG. 1, but with the cardown;

FIG. 4 is a large-scale horizontal section taken along line IV--IV ofFIG. 1;

FIG. 5 is a large-scale and partly sectional view of the detailindicated at V in FIG. 4.

SPECIFIC DESCRIPTION

As seen in FIG. 1 an elevator shaft 1 vertically traverses three storiesor floors 2, 3, and 4 that open into this shaft 1. A frame 5 at the topof the shaft 1 supports a pair of idler pulleys 6 over which is reeved acable 7 having one end attached to a car 8 and an opposite end connectedto a counterweight 9. This car 8 can move up and down on the shaft 1between two parallel and vertical rails 10 lying in a plane P. The car 8can communicate forwardly away from the plane with whichever of thefloors 2, 3, or 4 it is aligned with. The counterweight 9 is guidedbehind this plane P in vertical guide rails 9a and has a weight equal tothat of the empty car plus about 40% of the average load.

These rails 10 are identical and are as shown in FIG. 2 of T-section,each having a pair of arms fixed to the anchors 22 in the sides of theshaft 1 and a central leg formed as a rack with straight-across teeth 24(FIG. 1). The car 8 carries on its roof a pair of sprocket wheels 11lying in the plane P and rotatable about axes 11A perpendicular thereto.These sprockets 11 have teeth 28 complementary to and meshing with theteeth 24 and are each sandwiched between two large-diameter circulardisks 18 of a diameter substantially greater than the sprocket diameterso that they flank the leg of the respective rail 10 and substantiallyprevent the car 8 from moving horizontally perpendicular to the plane P.

Each sprocket 11 is in turn carried on a shaft 25 extending along therespective axis 11A and connected via a pair of bevel gears 17 toanother shaft 15 centered on an axis 15A parallel to the plane P andperpendicular to the axes 11A. This shaft 15 is journaled in pillowblocks 16 on the roof of the car 8 and is connected via a transmission13 to an electric drive motor 12 also carried on the car roof. Thisshaft also is connected to a brake 14 and to a governor or speed monitor20 both connected to a controller 21.

Underneath the car are two idler sprockets or wheels 19 similar to thesprockets 11. They may be provided with the brake 14 and/or speedregulator 20 according to this invention. They serve only to preventcanting of the car 8 about a horizontal axis perpendicular to the planeP.

With this arrangement the load will be carried by the teeth of the rails10 and sprockets 11. Since the two sprockets 11 are drivensynchronously, any irregularities will be reflected in a shift in theplane P, automatically equalizing the load on the two sprockets 11. Evenif the car 8 is loaded offcenter it will automatically shift slightly inthe plane P to equalize force on the two rails 10. If the teeth 24 and28 wear considerably, the only result will be that the car 8 will ride alittle lower than when they were new, but the arrangement will stilloperate smoothly and quietly. As a result wear is minimized, and wearwill not increase disproportionately when the teeth become worn.

According to a further feature of this invention, as seen in FIGS. 3 and4, the one idler sprocket 6 is actually carried on one end of a shaft 31journaled at 26 in the side wall of the shaft 1 in axial alignment withthe sprocket 6 and carrying at its outer end a sprocket 32 connected viaa chain 33 to another sprocket 34 journaled at 27 in the same shaftwall. The shaft 31, sprocket 6, and sprocket 32 are all rotatable abouta horizontal axis 6A lying in or parallel to the plane P.

As better seen in FIG. 5 this sprocket 34 is fixed to a bevel gear 35rotatable about an axis 35A parallel to the axis 6A but at the extremefront end of the shaft 1. Another bevel gear 36 carried on a shaft 37 isrotatable about a horizontal axis 36A perpendicular to the axis 35A andto the plane P. These gears 35 and 36 can be provided at the top of theshaft or, by suitable extension of the chain 33, anywhere therein, asthe coupling chain 33 lies wholly to the side of the moving parts.

The shaft 37 is also axially slidable in an inside plate 39 mounted inthe front wall of the shaft 1 and in an outside plate 40 received in apocket 42 formed beneath an access cover 43 provided on the front orpublic side of this wall. A coil-type spring 41 is engaged around theshaft 37 and is braced between the front face of the plate 39 and a ring38 fixed on the shaft 37, so as to urge this shaft 37 and the gear 36forwardly to bring the gears 35 and 36 out of engagement with eachother.

An actuating element such as a handwheel 45 has a collar 46 engageableover a polygonal-section end 44 of the shaft 37 to rotationally couplethe handwheel 45 and shaft 37. Engagement of the collar 46 over the end44 and pushing it backward along the axis 36A will compress the spring41 and engage the gears 35 and 36 together. In addition a front flange47 on the handwheel 45 can engage and actuate a switch 48 mounted in theback of the recess 42. This switch 48 is connected via the controller 21to the brake 14 to release it.

Normally the car 8 is provided with a trickle-charged battery that canoperate the brake 14 if power fails. In the event of such an emergencyit is nonetheless necessary to move a car 8 stranded between floors. Thecover 43 is removed and a handwheel 45 is fitted over the shaft end 44.The wheel 45 is then pressed in to engage the gears 35 and 36 anddisengage the brake 24 and is then turned in the appropriate directionto raise or lower the car 8.

Of course the elevator according to this invention can be provided withthe standard self-locking brakes that grab the rails 10 in the event ofcable failure, and the governor 20 can similarly be set up to operatethe brake 14 if the car speed exceeds 1.4 times its rated speed. Awiring harness connecting the drive motor and controller to the externalsource of power, door switches, and the like is also provided but is notshown here for clarity of view.

In addition a manual drive of the type shown in FIGS. 3 through 5 can beprovided in the car 3, effective on the shafts 12 or 25. The chainconnection can be replaced by a universal joint, and other obviouskinematic changes are of course also within the scope of this invention.

What is claimed is:
 1. An elevator for use in a multistory building, theelevator comprising:a pair of vertical and parallel rails forming avertical plane and formed with straight-across teeth; a car verticallydisplaceable between the rails; an idler wheel between the rails abovethe car; a cable looped over the idler wheel and having two ends, one ofwhich is attached to the car; a counterweight attached to the othercable end; respective sprockets rotatable on the car about axesperpendicular to the plane and having straight-across teeth meshing withthe rail teeth, the sprockets lying in the plane; drive means forsynchronously rotating the sprockets to vertically displace the caralong the plane on the rails; a hand-operable actuating element in thebuilding outside the car; and means including a transmission connectablebetween the element and the idler wheel for manually verticallydisplacing the car along the rails.
 2. The elevator defined in claim 1,further comprising means including guide disks fixed to and sandwichingthe sprockets, flanking the rails, and restricting movement of the carhorizontally only perpendicular to the plane.
 3. The elevator defined inclaim 1, further comprising:a brake on the car operatively engageablewith the sprockets.
 4. The elevator defined in claim 3 wherein themanual means includescontrol means connected between the element and thebrake for releasing same when the element is connected via thetransmission to the wheel.
 5. The elevator defined in claim 4 whereinthe transmission includes a pair of bevel gears engageable with eachother to couple the element to the wheel.
 6. The elevator defined inclaim 4 wherein the transmission includes a coupling chain.
 7. Theelevator defined in claim 4 wherein the manual means is operable fromthe uppermost story of the building.